spaceprovided) Spatial perception is a highly complex hierarchical problem. There are several parts of the brain that directly participate in spatial processing and code for different kinds of spatial reference frames. These regions work together to produce a complete, consistent representation of the environment. The goal of this study is to better understand the relationships and possible interactions between the egocentric (relative to animal's body) spatial reference frame in the parietal cortex and the allocentric (relative to the world) frame in the hippocampus, and to look for "signatures" in the activity of either region that mark transitions between alternative spatial frames in the other region. I plan to collect data simultaneously from large numbers of parietal and hippocampal neurons of a rat running on a track with variable shape to study the properties of firing activity in these regions and their responses to the changing geometry of the track. I plan to test the hypothesis that firing activity in parietal cortex is correlated with firing activity in CA1. In addition, I will work on mastering and extending a set of software tools based on the adaptive filtering algorithm used in Dr. Frank's laboratory, which allows accurate description of real time dynamics of neural spiking activity.